According to Wikipedia,

“Portrait photography or portraiture is a photography of a person or group of people that captures the personality of a subject by using effective lighting, backdrops, and poses. A portraiture picture might be artistic, or it might be clinical, as part of a medical study. Frequently, portraits are commissioned for special occasions, such as weddings or school events. Portraits can serve many purposes from usage on a personal Web site to display in the lobby of a business.”